Interspecific Ilex hybrid plant designated ‘Spartan’

ABSTRACT

A new and distinct variety of evergreen shrub holly distinguished in that it combines from three species ( Ilex rugosa, I. integra,  and  I. pernyi ), as well as exhibiting desirable landscape and production traits which distinguish it from other forms of  Ilex.  Plants of the new variety exhibit a moderately vigorous rate of growth, develop a dense, self-compacting, moderately broad conical form of moderate size, possess small, shiny, dark green leaves with a beautiful finely rugose surface and non-spiny margins (consumer friendly) with bright red fruit displayed on wood of the previous season&#39;s growth, and are outstanding for their high level of winter hardiness.

Latin name: Ilex rugosa×I. (integra×pernyi).

Cultivar name: ‘Spartan’.

BACKGROUND

The new cultivar is a result of a formal plant hybridization programconducted during the past forty-five years with many different speciesof Ilex for the purpose of developing new cultivars that are superiorand/or novel to Ilex cultivars current in the trade, and thus of highpotential for commercial distribution. The important selection factorsin this instance include superior winter hardiness, high vigor,excellent and novel foliage characteristics, and attractive fruitdisplay.

To our knowledge, plants of the combination of these three species havenot been previously reported.

SUMMARY

The variety was originated or discovered on a cultivated site at anagricultural experiment station or greenhouse in New Brunswick, N.J.08901, Middlesex County. Our invention is a novel, unique, and highlydesirable ornamental form of Ilex which was originated by us by crossingan unnamed and unpatented seedling of Ilex rugosa with a plant of thestaminate cultivar known as Ilex×(integra/pernyi) ‘Accent’. The varietywas asexually reproduced by cuttings and grafts.

The variety exhibits the following combination of traits:

-   -   (a) A moderately vigorous, dense and self-compacting evergreen        shrub of Ilex of semi-upright branching that becomes almost        conical with minimum pruning but becomes more rounded and        slightly columnar if the terminal leader(s) is removed in which        case the plant is easy to maintain at a desirable height.    -   (b) Evergreen leaves which are primarily ovate to elliptic with        attenuate base, rugulose surface, serrulate margin (consumer        friendly—no spines) and obtuse tip, and which are dark green and        shiny.    -   (c) An abundance of pistillate flowers well positioned on shoots        of the previous year's growth and providing a well distributed        set of fruit maturing to a bright red in the fall and then        persisting throughout the winter.    -   (d) Low susceptibility to disease and insect pests. In a        landscape setting, plants of ‘Spartan’ variety develop a dense,        self-compacting, conical growth habit and can be used as        foundation plants, as hedge plants, or even as a single specimen        since the plants are easy to maintain at a desirable height, are        evergreen with red fruit and are not plagued by insect pests or        disease organisms, all of which makes them useful in a wide        range of landscape settings.

The above-listed traits distinguish the Ilex rugosa×I. (integra×pernyi)‘Spartan’ from parent plants and known related cultivars. Additionaldistinguishing characteristics include winter hardiness, high vigor,novel foliage characteristics (in particular, the abundance ofpistillate flowers listed above), and fruit arranged in the axils ofeach lower leaf in an attractive display.

BRIEF DESCRIPTIONS OF THE DRAWINGS

This new cultivar of holly is illustrated by the accompanyingphotographic drawings, depicting the plant by the best possible colorrepresentation using color photography. The color definitions in thespecification have been taken from The R.H.S. Colour Chart of The RoyalHorticultural Society, London, England. The colors depicted are believedto be of a high level of fidelity and are believed to be as close to theactual coloration of the plant as possible in a photographicillustration of this quality. However, due to factors such as lightreflectance, cultural conditions and horticultural practices, thecoloration of this plant should be understood to be approximate. Forexample, the leaf color may vary depending on the composition and theconcentration of fertilizer that may be applied to the plant.

FIG. 1 illustrates the natural unpruned growth habit of the originalseedling of the new variety after two growing-seasons in containers pluseight growing-seasons in the field;

FIG. 2 illustrates typical foliage of the seedling plant after 10growing seasons (no fruit are present due to the absence of pollinatorplants in the field); and

FIG. 3 illustrates the foliage and fruit characteristics of a fruitedbranch on a three year cutting-grown plant of the new variety.

BOTANICAL DESCRIPTION

The following is a detailed description of our new cultivar of Ilex madefrom observation of the original seedling growing in the ground in thevicinity of New Brunswick, N.J. and of cutting-grown plants growing inthe ground at Princeton, N.J.

-   Parentage: Pistillate seedling of Ilex rugosa×Ilex×(integra/pernyi)    ‘Accent’.-   Pollinator: Plant may be pollinated by a staminate plant of    Ilex×aquipernyi or Ilex×meserveae with synchronous flowering period.-   Plant growth characteristics: The original seedling had an upright    conical habit, attaining a height of 2.13 m, and a basal width of    1.37 m which tapered to a width of 0.76 m at the apex after being    grown in a container for two growing seasons followed by eight    growing seasons in the field under conditions of minimal    fertilization and minimal supplemental irrigation. Diameter of the    tree trunk at 10 centimeters above the soil level was 5.9    centimeters at 10 years. Under more optimal growing conditions,    cutting-grown plants make vigorous growth (approximately 20 to 25    centimeters per year), becoming wider and more nearly columnar in    habit. With judicial pruning, a dense conical form can be maintained    readily if such is desired.

Growth rate of the plants varies based on climatic conditions and soiltype or artificial growing medium utilized and on cultural practicessuch as fertilization and supplemental irrigation. A plant in the maturephase (flowering) can be achieved in one year from a rooted cuttingtaken from a plant in the mature phase.

-   Foliage:    -   -   Type.—Evergreen, coriaceous and semi-glossy. Leaves            primarily ovate to elliptic with attenuate base, rugulose            surface and serrulate margins, and obtuse tip. Leaves borne            alternatively along stem at a density of one leaf per 9 mm            length of stem with the exception that the 2–3 terminal            leaves may be much smaller and positioned only 2–4 mm apart            on the stem.        -   Size.—Leaf size varies with light intensity and the program            of fertilization and supplemental irrigation. Typical size            averages 3–5 cm long and 2 cm wide.        -   Petiole.—Approximately 6.2 mm long and 1.2 mm wide, color is            Yellow-Green Group 144C.        -   Color.—Mature levels, upper surface — closest to Green Group            137A but a little greener and darker; undersurface — between            Yellow-Green Group 144C and 144D.-   Stems:    -   -   Color.—Tip 7.5 to 10 cm of new spring growth is Green Group            138A. One year old stems are Green Group 137C. Base of the            tree trunk is Green Group 137B.            Numerous dense branches at 45–60° angle. Current season's            growth varies from 2.5–4.0 mm in diameter and 15–30 cm in            length. Older wood progressively larger in diameter.-   Inflorescence and fruit:    -   -   Flowers.—Small on pedicels 3–4 mm in length borne on 1 mm            spurs in leaf axils of previous year's growth. Typically 5            mm diameter, fragrance — none detected, lastingness of bloom            approximately 6–8 days if pollination and fertilization            occurs as soon as flowers open; otherwise 10–12 days            depending on factors of weather such as sunlight,            temperature, wind and rain; corolla rotate, sepals 4–5 with            a shape of an equilateral triangle, all three sides being 1            mm in length with the apex of the pyramid appearing very            slightly rounded under magnification, margins being entire;            petals 4–5; petal oblong with a length averaging 3.19 mm,            width averaging 1.91 mm, base truncate, margin entire, apex            obtuse; buds form during August and September in the axils            of the leaves and appear as tiny nodules of tissues. In            following growing season, buds continue to develop and take            on a specific observable form which changes continuously in            shape, length and diameter until completely developed and            about to open; just prior to anthesis, the abaxial surface            of the petals is primarily Yellow-Green Group 150D with the            apical ¼ of the petal closest to Greyed-Red Group 178A. The            basal area of the adaxial surface of the petals of an open            flower is closest to but slightly whiter than White Group            150D with the apical ¼ of each petal being closest to            Greyed-Red Group 178B. The abaxial surface of the tiny            sepals Greyed-Purple Group 185A. The adaxial surface of the            anthers is Greyed-Purple Group 185A; the abaxial surface of            the sepals is Greyed-Purple Group 185B at the tip and Green            Group 138A at the base.-   Fruit:    -   -   Type.—Drupe containing 4, occasionally 5, woody pyrenes.        -   Size.—Basically rounded with a rather flat top,            approximately 7.0 mm in height and 8.0 mm in width.        -   Color.—At maturity, fruit are Red Group 46B, with a black            stigma.            Excluding the apical two or three leaves on the growth of            the previous season, the fruit borne singly on pedicels in            the axil of each lower leaf averages 5.34 fruit borne at the            axil of each leaf.-   Reproductive organ:    -   -   Pistil.—1; — Stigma 1; stigma is sessile on the ovary,            therefore, there is no style. Ovary — 1 with 4, occasionally            5 loculi. Stamens — 4 and occasionally 5, pollen not            produced as plant is pistillate, the filaments and anthers            that comprise the stamens being rudimentary.        -   Pedicel.—Length 3.0–4.0 mm; width 1.0 mm; color —            Yellow-Green Group 144C; ovary height 3.5 mm; width 3.5 mm;            color — Yellow-Green Group 144B; Stigma — height of 0.5 mm            and width of 2 mm; 4–5 lobed; color — in flower is            Yellow-Green Group 151C; on mature fruit color is            Greyed-Purple Group 187B; Filament — length 2.0 mm; width            0.5 mm; color closest to White Group 155D: Anther — length            0.5 mm; width 0.25 mm; color Greyed-Yellow Group 161B;-   Environmental tolerance: Field grown plants of this new variety    exhibit winter hardiness in U.S.D.A. Plant Hardiness Map    (January 1990) Zone 6a (−10° F.). No insect or disease damage has    been observed on plants growing in the field. Asexual reproduction    by cuttings of our new variety has been accomplished in the vicinity    of New Brunswick, N.J. The plant reproduces true to type in    successive generations of asexual reproduction.

1. A new and distinct interspecific hybrid shrub plant of Ilex,substantially as herein shown and described.